Rotary cutting blades are used for cutting fabric in quilt making, among other uses. Rotary cutting blades typically come in two standard sizes, the 45 mm diameter rotary cutting blade and the 60 mm diameter rotary cutting blade. An existing problem in the use of rotary cutting blades is the current high replacement cost of the blades for this popular fabric, craft and hobby cutting tool. Moreover, typical rotary cutting blades lack perfect roundness, wavering in radius as much as 2 mm out of perfect roundness. Existing products induce warping into the rotary cutter blade and therefore only sharpened quadrants of the blade's circumference. In addition, the abrasive strips intended to sharpen the cutting edge of the blade were actually falling off in the package because the adhesive had failed and this was before it was taken out of the package and used. In use, the blade cutting edge contact surface of the abrasive strip, to not be very robust and a groove quickly wore into it removing the abrasive particles thus creating a very short product life.
Existing products include large commercial circular blade sharpeners for meat slicing and the like. Also included were motorized commercial motor driven fabric cutters of various descriptions, and only the one manual sharpener for hand held rotary cutters mentioned herein.
The following represents a list of known related art:
Reference:Issued to:Date of Issue:U.S. Pat. No. 5,660,582TerrisAug. 26, 1997U.S. Pat. No. 5,499,943TerrisMar. 19, 1996U.S. Pat. No. 889,830Van BerkelJun. 2, 1908U.S. Pat. No. 1,051,646StukartJan. 28, 1913U.S. Pat. No. 1,165,342PetersonDec. 21, 1915U.S. Pat. No. 1,957,776GuryMay 8, 1934U.S. Pat. No. 1,310,700Hood et al.Jul. 22, 1919U.S. Pat. No. 1,977,418WinklerOct. 16, 1934U.S. Pat. No. 2,694,887Green et al.Nov. 23, 1954U.S. Pat. No. 2,721,430Green et al.Oct. 25, 1955U.S. Pat. No. 3,349,485BetcherOct. 31, 1967U.S. Pat. No. 4,373,302DarbyFeb. 15, 1983
The teachings of each of the above-listed citations (which does not itself incorporate essential material by reference) are herein incorporated by reference. None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed.
Existing art has a number of disadvantages, including the inability to adjust to accept rotary cutter blades of various small sizes for use in hand held rotary cutter tools. In addition, other prior art reviewed, does not maintain a precision alignment and support between the rotary cutter blade and the abrasive element, and in its current configuration, is incapable of creating a razor sharp edge consistently around the total circumference of a rotary cutter blade's cutting peripheral edge.
U.S. Pat. No. 5,499,943 discloses a rotary cutter blade sharpener where the rotary cutter blade is sandwiched between two clamping elements, which if they are not precisely flat and co-plainer could induce an out of flat condition onto a thin (approx. 0.020 thick rotary cutter blade) and create a shape not unlike a potato chip having high and low edges on the same side of the blade's peripheral circumference, making it impossible to sharpen with a rigid, angled, abrasive surface as shown. The isometric view (FIG. 4) is showing this prior art's radial, tapered, conical surface, having an abrasive strip affixed to it for the purpose of sharpening the rotary blade cutting edge, with no provision for replacement of this abrasive strip except by the purchase of a new device. Continued use of this device and its abrasive strip will shortly abrade it into an uneven, ringed, shape unable to support the sharpening process of the rotary blade's cutting edge. The rotary blade wears down through the abrasive material and it's adhesive backing, leaving no abrasive material available to sharpen the rotary blade's cutting edge, thus leaving the blade dull. In addition, my tests have concluded that the use of abrasive material such as claimed in this prior art, will breakdown very quickly after repeated use on the same contact point. Thus preventing the creation of a clean, sharp, burr free cutting edge on the rotary blade's cutting edge along with a very short usable product life span.
U.S. Pat. No. 5,660,582 discloses a radial, tapered, conical surface, having an abrasive strip affixed to it for the purpose of sharpening a rotary blade cutting edge, with no provision for replacement of the abrasive strip except by the purchase of a new device. Consistent and frequent sharpening of rotary blades of the same diameter, contacting this abrasive strip will create a groove at the point of contact with the rotary blade's cutting edge, and create a deformed area which will in turn create this same deformed shape onto the cutting edge of subsequent blades as they are rubbed in this distorted groove in the abrasive strip. Thus, creating a rounded, distorted, dull cutting edge, rather than maintaining the factory created cutting angle, shape, and sharp edge as with the present art. Additionally, the razor sharp edges are totally exposed to the operator while it is clamped into a blade handling device (FIGS. 6, 7, and 16). The risk is, if the clamped blade is dropped during use, that not only will the unprotected blade be possibly bent or chipped, and further dulled beyond repair. But it could cut the users shoe, bare foot, and expensive hardwood, tiled or carpeted floor. In use, user fingers can be cut on the rotary blade edge while trying to sharpen a blade per the user instructions included with the device. Also, it will be noted that the design and intended use of this prior art is as a hand held devise only, it can not be operated or used on a stable tabletop or work bench as with the present art. Also the clamping elements are shown with the surfaces for clamping the rotary cutter blade whereby the blade is sandwiched between these two clamping elements, which if they are not precisely flat and co-plainer could induce an out of flat condition onto a thin (approx. 0.020 thick rotary cutter blade) and create a shape not unlike a potato chip having high and low edges on the same side of the blade's peripheral circumference, making it impossible to sharpen with a rigid, angled, abrasive surface as shown. If the molding process and selected plastic materials are unable to produce a flat molded surface then it will not have the ability to clamp the rotary blade flat between them, which is the case with this prior art. The abrasive element shown is one of the critical components to the design of this prior art and its success as a viable and useful product. However, this prior art's radial, tapered, conical surface, having an abrasive strip affixed to it for the purpose of sharpening the rotary blade cutting edge, with no provision for replacement of this abrasive strip except by the purchase of a new device reduces its useful life and value to the customer. Continued use of this device and its abrasive strip will shortly abrade it into an uneven, ringed, shape unable to support the sharpening process of the rotary blade's cutting edge. The rotary blade wears down through the abrasive material and it's adhesive backing, leaving no abrasive material available to sharpen the rotary blade's cutting edge, thus leaving the blade dull. In addition, my tests have concluded that the use of abrasive material such as claimed in this prior art, will breakdown very quickly after repeated use on the same contact point. Thus preventing the creation of a clean, sharp, burr free cutting edge on the rotary blade's cutting edge along with a very short usable product life span.
Existing art has a number of other drawbacks, including the limited ability of these devices to adjust to accept rotary cutter blades of various smaller sizes for use in hand held rotary cutter tools. In addition, the need for a stationary, non-rotating, rotary cutter blade sharpener with a safety guard covering the blade and an abrasive element that is replaceable and capable of maintaining a precision alignment and support between the rotary cutter blade and the abrasive element, thus creating a razor sharp edge consistently around the total circumference of a rotary blade's cutting edge periphery, whereby the abrasive element is manually moved upon or around the stationary rotary blades cutting edge periphery to sharpen it. Reviewing prior art with these requirements in mind
U.S. Pat. No. 889,830 shows a device that is very complicated, and designed for large meat slicing machines whereby the large rotary blade is rotated against a sharpening element located in a fixed position and having no safety shield.
U.S. Pat. No. 1,051,646 is a sharpening device that rotates the large rotary cutter blade used in meat slicing, and sharpens the blade using two stationary held abrasive elements. The device is not adjustable for small rotary cutter blades and does not have a safety guard as an integral part of its design.
U.S. Pat. No. 1,165,342 is a sharpener for rotary blades that is not adjustable for small rotary cutter blades and has no safety shield while it rotates the large rotary cutter blade for sharpening as it holds the abrasive elements in a fixed position.
U.S. Pat. No. 1,957,776 discloses a cloth cutting electric powered rotary cutter that is intended for use as an attachment to an electric cloth cutting machine and in this application again rotates the rotary blade against a stationary mounted abrasive element and is not adjustable for various size manual rotary cutter blades, although it does have a blade guard.
U.S. Pat. No. 1,310,700 discloses a sharpener for slicing machine knives is shown and in this case the rotary blade is rotated to sharpen it as well, while the single wheel abrasive device is held in a stationary position. This device is also not intended for the smaller type rotary cutter blades and has no safety guard.
U.S. Pat. No. 1,977,418 discloses a knife sharpener device of a complicated nature that is intended for attachment to an existing cutting machine of some design and application. The device uses one abrasive element and one burr removing element that are affixed in a stationary location while the rotary blade is rotated in contact with these two elements to facilitate the blades sharpening. The nature of this prior art design dose not lend its self to the sharpening of the smaller type rotary cutter blades.
U.S. Pat. No. 2,694,887 discloses a deburring device for the sharpening of a rotary-slicing blade. It is also a device intended to be added onto an existing slicing machine or included in its design. In operation, the rotary blade is rotated while the deburring element is held stationary in order to facilitate the removal of burrs during the sharpening of a rotary blade.
U.S. Pat. No. 2,721,430 discloses a sharpener device for slicing blades that relates to an attachment to be adapted to a machine that uses a large size rotary cutting blade, in order to make easy the sharpening of the blade thereof. Again, the abrasive element is held stationary and the rotary cutter blade is rotated as it is in contact with said abrasive element, thus abrading the blade and sharpening it.
U.S. Pat. No. 3,349,485 discloses a combination of a rotary knife with sharpener wherein the described band type blade of the hand held rotary knife cutter has an included fixed position blade sharpening element which comes in contact with the blade while it is being rotated to sharpen said band type blade. The sharpening element however is not easily removable to change to different grits or for its replacement. This prior art design dose not lend its self to the sharpening of the smaller, disc type, rotary cutter blades.
U.S. Pat. No. 4,373,302 discloses a sharpening apparatus for circular blades, This is a commercial bench mounted device for large diameter circular blades and can not be adjusted for smaller diameter rotary cutter blades for hand held devices. The rotary blades are rotated against a stationary positioned power driven sharpening element for sharpening of the cutting edge. This design is not intended for being adapted to a hand held device as with the present art.
In summary, the reviewed prior art commented on herein, employs designs and materials that limit there application to devices for large diameter rotary blades that are table mounted and not adaptable for hand use on smaller size hand held rotary cutter knife blade sharpening. In some cases, because of design and material selection, the device's performance and operation is marginal at best and in some cases shortens the useful product life. In other cases the materials available at the time or selected, along with the manufacturing methods chosen, were not a good match for the device, or the design was limited by the knowledge and experience of the inventor. The wrong materials for the application, over complexity, weakness or flexibility of components, or poor choice of mechanical design for the desired application can make a product undesirable for manufacturing because of cost, design appearance, and esthetics. The application of state of the art materials, engineering methods and improved manufacturing methods as applied to the present invention, and described herein will overcome the failings of the reviewed prior art, to create an improved design of a device and methods of manufacture for an orbital, multi-size, rotary cutter blade sharpener having changeable, multi-grit, diamond coated abrasive elements as described herein.